Ice maker with thermal protection

ABSTRACT

An ice maker for use in freezing compartments of refrigerators and freezers provides a thermal cut-out or fuse to prevent damage in the event of overtemperature conditions. The thermal fuse is located in a closed compartment where it cannot be accidentally damaged or moved. A leaf spring provides an end engaging the thermal fuse to reliably hold the thermal fuse in good heat exchange relationship with the mold in which the ice cubes are formed. The ice maker also provides an improved mounting structure permitting support fasteners to be partially threaded into the wall of the freezer compartment before the ice maker is moved to its mounted position.

BACKGROUND OF THE INVENTION

This invention relates generally to ice makers for refrigerators, andmore particularly to such ice makers which incorporate novel andimproved thermal protection.

PRIOR ART

U.S. Pat. No. 4,833,894 describes an ice maker for use in refrigerators.Such ice maker provides an aluminum mold having a plurality of cavitiesin which water is frozen to form individual ice cubes. An electricresistance hearer is controlled by a thermostat and operates totemporarily heat the mold after the ice cubes are formed so that thebond between the ice cubes and the mold is released. This allows thecubes to be easily ejected from the mold.

Such ice maker is also described as providing a thermal cut-out or fusewhich shuts the unit off in the event that the heater causes excessivemold temperatures. The thermal fuse of the ice maker is mounted in apower lead and is positioned to sense and respond to the too excessivemold temperature.

Excessive mold temperatures can occur, for example, if the thermostatfails to open and shut the heater off when the mold temperature isreached sufficient to cause the melting of the ice cube along theinterface with the mold.

The thermal cut-out of such patent is in an exterior, relativelyunprotected position and is releasably held in heat exchangerelationship with the mold by a clip. The clip also is in contact withthe heater itself so it provides a relatively direct heat exchangerelationship between the heater and the thermal fuse.

If for any reason the thermal fuse is bumped and caused to move out ofthermal contact with the mold, it can fail to sense an overtemperaturecondition and fail to properly function. Such U.S. Pat. No. 4,833,894 isincorporated herein in its entirety to indicate what is believed to bethe most pertinent prior art.

SUMMARY OF THE INVENTION

The present invention provides a novel and improved control structurefor automatic ice makers of the general type described in U.S. LettersPat. No. 4,833,894. The ice makers provide a mold, usually aluminum,having cavities in which water is frozen to provide ice cubes. Such icemaker is intended to be installed in the freezing compartment of arefrigerator or freezer, and depends upon the temperature therein tocause the freezing of the ice cubes.

In order to permit easy ejection of the frozen ice cubes, a heater isprovided to heat the mold. This melts the ice along the interface withthe mold to eliminate the bond between the mold and the ice cubes. Thefrozen cubes are then ejected from the mold.

Automatic controls are provided so that the ice maker repeatedly andautomatically operates through cycles during which a thermostatdetermines that the water contained within the cavities of the mold isfrozen and initiates the operation of a heater to eliminate the bondbetween the ice cubes and the mold. The ice cubes are then ejected fromthe mold and water is then supplied to fill the cavities for subsequentfreezing.

Here again, a thermostat is provided in the control system to controlthe timing of the heater operation and the commencement of the automatedcycle of operation. When the thermostat senses a mold temperatureindicating that the water is frozen, it closes to initiate heateroperation and to initiate the operation of the motor which powers theejection system. Thereafter, when the temperature of the mold is raisedto a level above freezing to indicate that a bond is destroyed, thethermostat again opens and terminates the operation of the heater.

In order to prevent excessive mold temperatures in the event that thethermostat fails to open and terminate the operation of the heaters, thecontrol system provides a thermal cut-out or fuse. In accordance withthe present invention, the thermal fuse is positioned directly againstthe surface of the mold and is positioned so that it is insensitive tothe temperature of the heaters. Further, the thermal fuse is mountedwithin an enclosure structure where it cannot be accidentally damaged ormoved out of heat exchange relationship with the mold. Further, themounting of the thermal fuse is such that the thermal fuse isresiliently held in positive heat exchange relationship with the moldfor accurate and reliable operation.

Another aspect of this invention involves the mounting of the ice makerwithin a refrigerator in which fasteners can be initially inserted priorto the installation of the ice maker. This facilitates the easy mountingof the ice maker within the freezing compartment of a refrigeratorcabinet.

With the present invention, a simple structure is provided to reliablyprevent overtemperature conditions and to protect against damageresulting from malfunction of the automatic thermostat normally operableto control the cyclic operation of the ice maker. In addition, animproved mounting structure is provided for ease of installation andremoval of the ice maker within the freezer compartment of arefrigerator or the like. These and other aspects of the invention areillustrated in the accompanying drawings and more fully described in thefollowing specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, perspective view of an ice maker in accordancewith the present invention, installed in a typical refrigerator havingan upper freezer compartment;

FIG. 2 is an enlarged, perspective view illustrating the ice maker perse with the cover removed from the control enclosure;

FIG. 3 is a perspective view similar to FIG. 2 but illustrating furtherdisassembly of the control enclosure;

FIG. 3a is an enlarged view of the portion of the control circuitillustrated in FIG. 3 with the elimination of some of the elementsthereof for purposes of simplifying the illustration of the presentinvention;

FIG. 4 is an enlarged, fragmentary cross section, taken along line 4--4of FIG. 3a;

FIG. 5a is an enlarged fragmentary view illustrating the structure of animproved mounting system for the ice maker; and

FIG. 5b is a cross section taken along line 5b--5b of FIG. 5a.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a typical installation of an ice maker 10incorporating the present invention in the freezer compartment 11 of arefrigerator 12. In such an installation, water is supplied to a mold 13having a plurality of cavities in which the water is held while itfreezes to form the ice cubes. An automatic control system is providedwithin a control housing assembly 14 mounted at one end of the mold 13.Along one side of the mold 13 is an array of stationary fingers 16. Anarray of ejector fingers is pivoted for rotation about an axis 15 andoperate to eject ice cubes from the mold. The ejector fingers interleavewith the stationary fingers and cooperate therewith to cause the icecubes to be deposited in a bin 19 below the ice maker. The controlsystem provides a motor connected to rotate the array of ejector fingers17. A stop wire 21 is connected to the control system so that theautomatic operation of the ice maker is terminated when sufficient icecubes are located within the bin 19.

The ice maker thus far described is common to prior art ice makers andis familiar to those skilled in the art.

Referring now to FIGS. 2 through 4, the control housing assembly 14includes a cover or cap member 22 which, when installed as illustratedin FIG. 1, completes the enclosure of the control system for the icemaker. However, in FIG. 2, the cover 22 is shown removed from theremainder of the control housing assembly. When the cover 22 is removed,a motor plate 23 is exposed. The electric motor (not illustrated) ismounted on the inner side of the motor plate 23 and provides an outputgear 24 which meshes with and drives a gear 26 connected to rotate theejector fingers about the axis 15.

When the motor plate 23 is removed, the interior of the main housingmember 28 is exposed to expose the electrical components of theautomatic control system, as best illustrated in FIGS. 3, 3a and 4. Inthese figures, components of the control system which are notsignificant with respect to the present invention per se have beeneliminated to make the drawings illustrating the invention easier tocomprehend.

As best illustrated in FIG. 3a, the control system includes a number ofcomponents mounted on the non metallic inner wall 29 of the main housingmember 28. The main housing member 28 is bolted to the end of the mold13 so that the inner wall 29 of the housing member is in face-to-faceabutment with the surface 31 of the end of the mold 13, as illustratedin FIG. 4. Projecting through the end wall of the mold and the innerwall 29 of the main housing member 28 is the end of the shaft 32 fromwhich the ejector fingers 17 project. That shaft is connected to thegear 26 when the motor plate 23 is installed and is rotated around theaxis 15 during a portion of the cycle of operation, as discussed below.

Also mounted on the inner wall is a pivoted lever 33 which is connectedto one end of the stop wire 21. The lever operates a shut-off switch toprevent cycling of the ice maker when the bin 19 is full.

A U-shaped heater 36 has end terminals 36a and 36b which project throughthe inner wall 29 into the interior of the control housing assembly. Theheater extends back along the mold along each bottom side edge thereofand across the mold at the end thereof remote from the control housingassembly 14. Such heater is positioned in good heat exchangerelationship with the mold so as to heat the mold during a portion ofthe cycle of operation of the ice maker.

A pair of temperature sensors 37 and 38 are mounted in the inner wall 29and respectively project through openings 41 and 42 formed therein sothat they engage and are in direct heat exchange relationship with theend surface 31 of the mold, as best illustrated in FIG. 4. The sensor 37is an automatic thermostat of the type which closes at a predeterminedlow temperature and opens at a predetermined higher temperature. Thetemperature sensor 38, on the other hand, is a thermal fuse or thermalcut-out device which remains closed during the normal operation of thesystem but opens and remains open when an excessive temperature occursin the mold. The thermal fuse operates to prevent damage to therefrigerator and other components of the system in the event of afailure, for example, caused by failure of the thermostat 37 to open.

In order to ensure that the maximum thermal exchange relationship ismaintained between the two temperature sensors 37 and 38 and the endsurface 31 of the mold 13, a heat-conductive, greaselike material 43 ispositioned between each of the temperature sensors and the surface 28 toensure good intimate heat transfer characteristics. In FIG. 4, thethickness of such material 43 is exaggerated so that its presence can beillustrated.

The thermal cut-out 38 is held in the opening 42 and is resilientlybiased toward the surface 31 by a leaf spring 44. One end of the springis mounted on the housing and the other end engages the thermal fuse onthe side thereof opposite the mold. The spring provides a resilientforce reliably maintaining contact between the thermal fuse and moldeven when thermal expansion and contraction occur. Consequently, thethermal fuse operates reliably to prevent overtemperature damage.

It is important to mount the thermal cut-out at an interior protectedposition where it cannot be accidentally damaged or moved from its heatexchange relationship. It is also important to mount the thermal cut-outin such a position that it does not sense the temperature of the heaterper se in any way, and therefore is not subject to premature operation.If, for example, a heat exchange relationship between the heater and thethermal cut-out existed, premature operation of the thermal cut-outwould likely occur since the heater inherently reaches a highertemperature than the mold even when the system is functioning properly.

FIGS. 5a and 5b illustrate an improved mounting system for the ice makerwhich promotes ease of installation. In the past, it has been necessaryto position the ice maker in its installed position and then installfasteners threaded into the wall of the refrigerator to complete themounting. In accordance with this preferred mounting system, thefasteners are threaded part way into the wall. The ice maker is thenpositioned with its mounting legs 51 above the previously installedfasteners 52. The ice maker is then lowered so that the mounting legsmove down along the sides of the shank of the fasteners 52 with the headcleared between two side walls 53 and 54. When the unit is lowered to aposition into which the shanks of the fasteners engage the associatedsemicircular wall 56, the heads of the fasteners overlay the adjacentportions of the mounting legs and installation is completed by merelytightening the fasteners.

With the preferred embodiment of the present invention, the ice makercontrol circuit operates through repeated cycles starting when the waterwithin the mold 13 is frozen. This is determined by the thermostat 37sensing a mold temperature below freezing, preferably about 15 degreesFahrenheit. When that occurs, the thermostat closes and simultaneouslyinitiates the operation of the mold heater 36 and the motor (notillustrated). The initial rotation of the motor causes a cam on the gear26 to close a hold switch. The gear reduction of the motor driving theejection fingers is such that they do not move from the positionillustrated in FIG. 3 past the stationary fingers 16 until a sufficienttime has elapsed to allow the energized heater to melt the water at theinterface between the ice cubes and the mold surface. After the bondbetween the ice cubes and the mold has released, the ejection fingersrotate down into the mold and around the eject the ice cubes out overthe stationary fingers 16 and into the bin.

When the thermostat senses a mold temperature above the freezingtemperature, ensuring that such bond has been released (preferably about40 degrees Fahrenheit), the thermostat 37 again opens to terminate theoperation of the mold heater 36. The motor continues to operate until itreaches the parking position of the ejector finger 17. A cam-operatedhold switch opens to terminate the operation of the motor until thebeginning of the next cycle. As is customary in these devices, acam-operated water-fill switch is operated to fill the mold after thefrozen ice cubes have been ejected therefrom so that a subsequent groupof ice cubes can be formed.

With this invention, an ice maker is provided which is reliablyprotected against overtemperature conditions. The thermal cut-out orfuse 38 is located in a completely protected position where user contactcannot dislodge it from position. Further, it is spring-biased intoreliable heat exchange relationship with the surface of the mold at alocation substantially spaced from the heaters. Therefore, it reliablysenses the temperature of the mold and is not affected by the highertemperatures of operation of the heaters which exist before the desiredmold temperature is reached.

Preferably, the thermal cut-out is selected to operate at a temperatureof at least about 170 degrees Fahrenheit, which is above the temperaturelikely to be encountered by the ice maker during storage and shipment ofthe unit prior to its installation and operation within the freezingcompartment. This ensures that the thermal cut-out device will not beactivated to its open condition prior to installation of the associatedice maker.

Although the preferred embodiment of this invention has been shown anddescribed, it should be understood that various modifications andrearrangements of the parts may be resorted to without departing fromthe scope of the invention as disclosed and claimed herein.

What is claimed is:
 1. An ice maker for refrigerators comprising a moldformed of thermally conductive metal, said mold having a cavity in whichwater is held and frozen when said mold is exposed to a subfreezingenvironment, heater means in heat exchange relationship with said mold,controls for said ice maker including a thermostat connected to activatesaid heater means when the water in said cavity freezes forming an icecube, said heater means operating to melt ice along its interface withsaid cavity to release the bond between said ice and mold and permitremoval of said ice cube from said cavity, said thermostat operating toterminate operation of said heater means when said mold reaches a firstpredetermined temperature at least high enough to melt said ice alongsaid interface, said controls also including a thermal fuse positionedagainst said mold in direct heat exchange relationship therewithoperating to terminate the operation of said heater means when thetemperature of said mold reaches a second predetermined temperaturesubstantially above said first predetermined temperature, and enclosuremeans enclosing the controls for said ice maker including saidthermostat and thermal fuse along with portions of said mold in heatexchange relationship therewith to ensure that said heat exchangerelationship between said mold and thermal fuse is maintained, said moldbeing elongated having an end, said enclosure means including anon-metallic inner wall having portions engaging said end or said mold,said inner wall having openings therein exposing portions of said end ofsaid mold, said thermostat and said thermal fuse being positioned insaid opening in direct heat exchange relationship with said end of saidmold.
 2. An ice maker as set forth in claim 1, wherein said controlsinclude spring means resiliently biasing said thermal fuse into directengagement with said mold.
 3. An ice maker as set forth in claim 2,wherein sad thermal fuse engages said mold at a location substantiallyspaced from said heater means.
 4. An ice maker as set forth in claim 1,wherein said thermal fuse engages said mold at a location spaced fromsaid heater means to prevent a direct exchange relationship between saidthermal fuse and said heater means.
 5. An ice maker as set forth inclaim 1, wherein said second predetermined temperature is higher thannormal environmental temperatures of said ice maker to prevent prematureoperation of said thermal fuse.
 6. An ice maker as set forth in claim 1,wherein said controls include an elongated leaf spring mounted at oneend on said enclosure means and having its other end engaging the sideof said thermal fuse opposite said mold, said leaf spring resilientlyurging said thermal fuse toward said mold reliably maintaining heatexchange relationship therewith during thermal expansion and contractionof the components of said ice maker.
 7. An ice maker as set forth inclaim 1, wherein said mold provides mounting legs installable andremovable on fasteners threaded into the wall of said refrigerator unitwhereby said fasteners can be partially threaded into said wall beforesaid ice maker is installed.
 8. An ice maker comprising an aluminum moldhaving cavities in which water is frozen to form ice cubes, a heater inheat exchange relationship with said mold operable to heat said mold andmelt said ice cubes along the interface therewith to allow removal ofsaid ice cubes from said mold, a non-metallic control housing having aninner wall in abutting relation with a portion of said mold and defininga closed chamber, said inner wall having openings therein exposingsurface portions of said aluminum mold to said chamber, controls in saidchamber including a first control positioned in an opening in said innerwall operable to energize said heater when ice cubes are frozen in saidcavities and to subsequently de-energize said heater, and a thermal fusein said chamber mounted in an opening in said inner wall abutting anadjacent surface of said mold and operating to de-energize said heaterwhen excessive temperatures occur.
 9. An ice maker as set forth in claim8, wherein a spring mounted in said cavity provides an end engaging saidthermal fuse on the side thereof opposite said mold resiliently urgingsaid thermal fuse into direct heat exchange relationship with said mold.10. An ice making system comprising a refrigerator having a compartmentmaintained at sub-freezing temperatures, an ice maker mounted in saidcompartment, said ice maker including an aluminum mold having cavitiesin which water is frozen to form ice cubes, a heater in heat exchangerelationship with said mold operable to heat said mold and meld said icecubes along the interface thereof with said cavities to allow removal ofsaid ice cubes from said mold, a control housing having an inner wall inabutting relationship with a portion of said mold and defining a closedchamber, controls in said chamber including a first control operable toenergize said heater when said ice cubes are frozen in said cavities andto thereafter de-energize said heater, and a thermal fuse mounted insaid inner wall abuting an adjacent surface of said mold, said thermalfuse operating to de-energize said heater when excessive moldtemperatures occur, said inner wall being non-metallic and havingopenings therein exposing portions of said mold, said first control andsaid thermal fuse being positioned in said openings in direct heatexchange relationship with said mold. .Iadd.
 11. An ice maker formounting in the freezer compartment of refrigerators comprising anelongated mold formed of thermally conductive material, said mold havinga cavity in which water is held and frozen when exposed to subfreezingenvironment, a heater in heat exchange relationship to said moldoperable to melt ice along its interface with said cavity to release thebond therebetween and allow removal of the ice from said cavity, powermeans connected to eject said ice from said cavity when said heaterreleases said bond between said cavity and said ice, said mold providinglaterally extending mounting legs at spaced locations along the lengthof said mold for mounting said ice maker on the wall of said freezercompartment, each of said mounting legs providing a face portion havinga slot therein open at one end, said face portion being spaced from theadjacent side of said mold and connected to said adjacent side by a pairof substantially parallel wall portions extending between said faceportion and said adjacent edges of said mold with one wall portionlocated on each side of the associated slot, said ice maker beinginstallable on headed fasteners threaded partially into said wall ofsaid freezer compartment by positioning said face portion against saidwall and moving said legs along said wall causing said fasteners to movethrough the associated opening into the associated slot, said fastenerheads passing between the adjacent wall portions..Iaddend. .Iadd.
 12. Anice maker as set forth in claim 11, wherein said heads are accessibleafter said mold is mounted on said fasteners permitting tightening andloosening of said fasteners..Iaddend. .Iadd.13. An ice maker as setforth in claim 11, wherein said slots provide opposed side walls whichdiverge as they extend toward said openings..Iaddend. .Iadd.14. An icemaker as set forth in claim 12, wherein said ice maker is adaptablymounted on a vertical side wall of a freezer compartment of arefrigerator and wherein said face portions extend vertically, saidslots being open at the bottom end thereof, and said ice maker isinstalled by moving said face portion down along said side wall causingsaid fasteners to pass through said openings into the associated slot,said fasteners being accessible over the top of said mold when said icemaker is installed..Iaddend. .Iadd.15. An ice maker as set forth inclaim 11, wherein said ice maker provides a housing at one end of saidmold enclosing said power means, said housing tending to block access tosaid fasteners when said ice maker is installed..Iaddend. .Iadd.16. Arefrigerator providing a freezer compartment having a verticallyextending side wall, an ice maker mounted in said freezer compartmentagainst said side wall, said ice maker providing a mold having a cavityin which water is held and frozen when exposed to a subfreezingenvironment within said freezing compartment, a heater in heat exchangerelationship to said mold operable to melt ice along its interface withsaid cavity to release the bond therebetween and allow removal of icefrom said cavity, power means connected to eject said ice from saidcavity when said heater releases said bond between said cavity and saidice, said mold providing laterally and upwardly extending legs at spacedlocations along the length of said mold for mounting said ice maker onsaid side wall of said freezer compartment, each of said mounting legsproviding a face portion having a slot therein open along the lower edgeof said face portion, said face portion being spaced from the adjacentside of said mold and connected to said adjacent side of said mold by apair of substantially parallel wall portions extending between said faceportion and the adjacent edge of said mold with one wall portion locatedon each side of the associated slot, said ice maker being installable onfasteners threaded partially into said wall of said freezer compartmentby positioning said face portion against said side wall and moving saidlegs downwardly along said wall causing said fasteners to move into saidslots through said openings therein, said fasteners providing headspassing between the adjacent of said wall portions, said fasteners beingaccessible over the top of said mold when said ice maker is in saidinstalled position..Iaddend.